14. IGRP, EIGRP: IGRP and EIGRP
are proprietary of Cisco. These
two protocols use composite
metric to determine the best
path to a remote network.
-
IGRP (as well as
EIGRP) use the following
components as metrics:
1.
Delay: Calculated by
adding up the delay along the
path to the next router.
2.
Reliability: This is
representative of how many
errors are occurring on the
interface. The best reliability
value is 255. A value of 128
represents only 50% reliability.
3.
Load: Load metric also
has a range from 1 to 255. If a
serial link is being operated at
50% capacity, the load value is
255X0.5 or 12.5. Lower load
value is better.
4.
MTU: Stands for Maximum
Transmit Unit size, in bytes.
Ethernet and serial interface
has a default MTU of 1500.
Larger MTU size means that the
link is more efficient.
5.
Bandwidth: The bandwidth
is specified in Kbps. Larger the
bandwidth, better the link.
EIGRP (as well as IGRP) uses
Bandwidth and Delay as default
criteria to determine the best
path.
-
show ip route
eigrp: Displays the current
EIGRP entries in the routing
table.
-
Show ip eigrp
traffic: This command can be
used to learn the number of
EIGRP packets sent and received.
-
The neighbor table
in EIGRP include the following
fields:
1.
Neighbor address: This is
the network layer address of the
neighbor router.
2.
Queue: This represents
the number of packets waiting in
queue to be sent.
3.
Smooth Round Trip Time
(SRTT): This represents the
average time it takes to send
and receive packets from a
neighbor. This timer is used to
determine the retransmit
interval (RTO).
4.
Hold Time: This is the
period of time that a router
will wait for a response from a
neighbor. If there is no
response at the end of this time
period, the link is considered
unavailable.
